Bearing device for roll of hot dipping bath in continuous hot dip coating line

ABSTRACT

In a bearing device for a roll of a hot dipping bath, i.e., zinc pot, a sleeve is fastened to a shaft of the roll of the hot dipping bath in a continuous hot dip coating line, i.e., a continuous galvanizing line. A bush housing has a bush internally fixed to support the sleeve, and a curved annular outer surface. Also, bush housing fixed rings are fixed to both inner sides of a fixed ring housing which is associated with a rig of the hot dipping bath roll. Each of the bush housing fixed rings has a curved annular inner surface supporting the bush housing at both sides thereof and in abutment with the curved annular outer surface of the bush housing. The invention allows the steel sheet to be coated with molten metal stably and speedily with high efficiency. Also, the bush and sleeve of the bearing device are not locally worn away, thereby extending useful life of the roll.

TECHNICAL FIELD

The present invention relates to a roll of a hot dipping bath such as astabilizing roll which is submerged in the hot dipping bath for coatinga steel sheet with molten metal to support a transferred steel sheet.

More particularly, the present invention relates to a bearing device fora roll of a hot dipping bath, i.e., a roll of a zinc pot in a continuousgalvanizing line which effectively prevents vibration of a bearing partcaused by local wear of parts thereof to ensure faster coating of thesteel sheet, extends useful life of the roll and enables higher qualitycoating of the steel sheet.

BACKGROUND ART

In general, another second metal layer is plating on a metal steel sheetby electrical-chemical treatment or using a hot dipping bath which has asecond metal for coating molten therein and then a steel sheet submergedtherein.

A representative molten metal coating adopts galvanized steel sheet.That is, the steel sheet, to be galvanized, passes around rolls of azinc pot roll filled with molten zinc.

Especially, a continuous galvanizing line (CGL) allows the steel sheetto continually pass around the zinc pot roll to have its surface coatedwith zinc.

A galvanized steel sheet was utilized as a construction materialinitially. However, recently the steel sheet has been more extensivelyused, for example, in various assortments of electronic products orautomobile materials due to endurance of harsh process conditions andmass producibility thereof.

Therefore, with its use broadened to electronic products or automobilematerials where surface quality is crucial, the steel sheet faces anincreasingly higher standard for better hot dip coating, i.e., toenhance surface glossing, corrosion resistance, weldability orcoatability.

FIG. 1 illustrates a roll of a zinc pot in a continuous galvanizing line(CGL) and internal equipment thereof.

That is, as shown in FIG. 1, a steel sheet 200 is continuously suppliedfrom a pay-off reel (not illustrated) to be connected to a heatingchamber and induced to the zinc pot (bath) 220 filled with molten zinc222 through a snout 210 immersed below a molten level of the zinc pot220.

Also, the steel sheet 200 starts to pass perpendicularly toward an upperpart of the zinc pot by virtue of the zinc pot roll immersed in the zincpot 220, i.e., a sink roll 230 and stabilizing rolls 240 disposed justthere over.

That is, the molten zinc 222 filled in the zinc pot 220, is attached andcoated onto a surface of the steel sheet 200.

Here, the steel sheet 200 that passes around the sink roll 230 passesbetween the pair of stabilizing rolls 240 disposed just there over andthese stabilizing rolls serve to prevent warping of the steel sheet.

Then, the steel sheet 200 passes between a pair of air knives 250disposed just above the molten level of the zinc pot, thereby adjustablyattached with molten zinc.

Then, the steel sheet is cold solidified and wound into a coil through atension reel (not illustrated).

Therefore, the sink roll 230 and stabilizing rolls 240 of FIG. 1 aresubmerged in molten zinc (molten metal) of the zinc pot (hot dippingbath). The sink roll 230 and stabilizing rolls 240 guide a direction ofthe passing steel sheet 200 or corrects bending of the steel sheet whichoccurs when the steel sheet submerged in a high temperature zinc pot(zinc bath) emerges over the molten level.

For example, as shown in FIG. 1, the steel sheet 200 is connected to theheating chamber and passes through a sealed tube type of snout 210 whichis submerged in the molten level of the zinc pot. Subsequently, thesteel sheet 200 changes its motion toward a perpendicular upwarddirection due to the sink roll 230. Then the pair of stabilizing rolls240 disposed just over the sink roll 230 imposed pressure on front andback surfaces of the steel sheet 200 transferred there between.

Accordingly, the sink roll 230 and the stabilizing rolls 240 suppresswarping, distortion, inflection or vibration of the hot steel sheet 200.

Yet the zinc pot roll (sink roll 230 and stabilizing rolls 240) isdifferent from a driving roll. That is, the zinc pot roll is immersed inthe zinc pot 220 filled with hot molten zinc having a temperature ofabout 450° C. to 460° C. to operate while the driving roll runs at aroom temperature.

Also, the zinc pot roll is not driven by a separate driving source, androtated by a force of the transferred steel sheet, contacting the steelsheet without being powered. Therefore, tension load varies withthickness and width of the passing steel sheet 200.

Meanwhile, referring to FIG. 1, the sink roll 230 is spaced apart from adeviation roll (not illustrated) disposed over a cooling zone at adistance of 50 m to 60 m. This range of distance leads to loss oftension or inaccuracy of transfer of the steel sheet, thereby causingthe steel sheet to vibrate severely.

Accordingly, the stabilizing rolls 240 installed just over the sink roll230 critically serve to correct vibration or deformation such asinflection of the steel sheet when transferred.

However, the steel sheet produced by the steel manufacturer has variousthickness and width ranging from 0.4 mm to 2.3 mm and 800 mm to 1860 mm,respectively. Thus one of the stabilizing rolls 240 (left side ofFIG. 1) is fixedly disposed and the other one (right side of FIG. 1) ismovably disposed.

For example, as shown in FIG. 2, one of the stabilizing rolls 240 a isfixed to a rig 250, and the other one 240 b is associated with a movablearm 260 which moves forward and backward by a driving source such as ahydraulic cylinder and a driving motor and installed on the rig so as toproperly correct the steel sheet in accordance with thickness and widththereof.

Moreover, the sink roll 230 is engagingly disposed under the rig 250.

Thus, the rolls 230, 240 a and 240 b are introduced into or ejected fromthe zinc pot integrally with the rig 250.

But as shown in FIGS. 1 and 2, the stabilizing rolls having a smallerdiameter and greater length than the sink roll are immersed in themolten metal 222 having a high temperature of at least 450° C. whenrotating. Consequently, the stabilizing rolls are bent and deformed bytension of the steel sheet 200 and have a central line of the roll shaftinclined.

For example, FIG. 3 is a schematic diagram for analyzing actual loaddistribution of the stabilizing rolls 240 which are submerged in thezinc pot during operation.

As shown in FIG. 3, the stabilizing rolls with a shaft having a diameterof 50 mm to 70 mm keep a central shaft line of C1 before being affectedby tension of the steel sheet and then have the central shaft linetilted toward C2 under influence of tension.

Then, FIG. 4 illustrates a conventional hot dipping bath roll in acontinuous galvanizing line, especially stabilizing rolls 240 and abearing part.

That is, as shown in FIG. 4, a bush 243 of the bearing part supporting asleeve 242 fixed to a shaft 241 of the roll is fastened to a fixed bushhousing 244. The fixed bush housing 244 is fixed onto a frame 245associated with the rig 250 just described.

Accordingly, as shown in FIGS. 3 and 4, the stabilizing rolls in theconventional zinc pot tend to experience a tilt in their central shaftline owing to bending resulting from tension of the steel sheet.However, the bearing part cannot compensate for the inclination of thecentral shaft line.

For example, FIG. 4 illustrates a structure in which the bush 243 isformed integral with the fixed bush housing 244. Here, the sleeve 242 ofthe roll shaft 241 is in local contact with the bush 243 and thus easilyinserted thereinto.

Therefore, the roll shaft rotated increases local friction between thesleeve and bush so that the roll itself fails to rotate smoothly.

Moreover, stiff rotation of the roll shaft 241 causes a skid in acontact area between the stabilizing rolls 240 and the steel sheet 200.

As a result, the slide between the steel sheet and the rolls leads tosurface defects of the steel sheet.

The zinc pot rolls, i.e., zinc pot rolls such as the sink roll orstabilizing rolls rotate only by friction between the steel sheet andthe roll surfaces in the zinc pot 220 filled with molten metal without aseparate driving source. Thus, the stabilizing rolls rotate with reducedrotation force owing to viscous resistance or sliding friction of theroll bearing part.

Typically, viscous resistance and sliding friction are proportionallyincreased by relative velocity of an object. Therefore, the zinc potroll is rotatable only when friction between the steel sheet and theroll surface is greater than the sum of viscous resistance and slidingfriction of the bearing part.

In an actual assembly line of the steel manufacturing, the steel sheet200 passes the zinc pot faster to increase production speed of the hotdip coated, i.e., galvanized steel sheet. But resistance friction asjust described surpasses rotation force, thereby causing a skid betweenthe roll and steel sheet. That is, the steel sheet to be galvanized inthe zinc bath can hardly move faster in the actual assembly line.

Consequently in the zinc pot roll, as shown in FIG. 3, it is imperativeto correct bending of the rolls and prevent local contact between thesleeve and bush.

Although not illustrated in a separate drawing, another conventionalbearing part of a hot dipping bath roll is disclosed in U.S. Pat. No.5,549,393 to overcome problems associated with such a conventional hotdipping bath roll.

For example, although not illustrated in a separate drawing, FIG. 6 ofthe U.S patent teaches a hot dipping bath roll which includes aretainer, a sleeve and a bearing ring. The retainer has a sphericalannular convex surface. The sleeve has a frusto-conical concave annularsurface which movably supports a left annular outer surface of theretainer and is supported by a housing. The bearing ring has an annularconcave frusto-conical surface which movably supports a right annularouter surface of the retainer.

Therefore, in the roll according to the aforesaid document, thespherical annular convex surface of the retainer is in point contactwith the frusto-conical concave annular surface of the sleeve (by thefrusto-conical concave annular surface). Thus, practically, a contactarea between the retainer and sleeve sustains load intensively, therebyresulting in local deformation.

In addition, sliding friction arising between the retainer and sleevebrings about local friction, thereby aggravating vibration of the rollrotated.

DISCLOSURE OF INVENTION Technical Problem

The present invention has been made to solve the foregoing problems ofthe prior art and it is therefore an object of the present invention toprovide a bearing device for a roll of a hot dipping bath in acontinuous hot dip coating line which prevents eccentric spacing oreccentric rotation despite long-time use, thereby suppressing vibrationof a steel sheet resulting from wobbling of a roll shaft and allowingthe steel sheet to be coated smoothly even during fast transfer thereof.

Technical Solution

According to an aspect of the invention for realizing the object, thereis provided a bearing device for a roll of a hot dipping bath,comprising: a sleeve fastened to a shaft of the hot dipping bath roll ina continuous hot dip coating line; a bush housing having a bushinternally fixed to support the sleeve, and a curved annular outersurface; and bush housing fixed rings fixed to both inner sides of afixed ring housing which is associated with a rig of the hot dippingbath roll, each of the bush housing fixed rings having a curved annularinner surface supporting the bush housing at both sides thereof and inabutment with the curved annular outer surface of the bush housing.

Preferably, the curved annular outer surface of the bush housing isconvex spherical surface and the curved annular inner surface of thefixed ring is concave spherical surface to be in surface contact withthe convex spherical surface of the bush housing.

Preferably, the bearing device further includes a bush housing ringengaged with an end of the bush housing to fix the bush.

More preferably, the bearing device further includes a buffer filminterposed between the bush housing and the housing ring and between thebush housing and an edge of the bush.

The bearing device further includes inner and outer fixed rings and ashell housing disposed at both sides of and fixed to the fixed ringhousing and the bush housing fixed rings, the shell housing fixedlyengaging with the rig of the hot dipping bath roll.

Preferably, the bearing device further includes gaskets interposedbetween the inner fixed ring and the shell housing and between the outerfixed ring and the shell housing to block molten metal from penetratinginside.

The bearing device further includes a fixed pin inserted through thefixed ring housing and into a pin hole of the bush housing to preventwear resulting from rotation of the bush housing.

Also, the bearing device further includes first and second cover memberscovering from a lower end of the bush housing to the bush housing fixedrings to block molten metal from penetrating inside.

Preferably, the first cover member has an inner side fixed to thebushing housing and an outer side fixed between the bush housing ringand the inner fixed ring and the second cover member has an inner sidefixed to the opposing bush housing fixed ring and an outer side fixedbetween the bush housing fixed ring and the outer fixed ring.

Preferably, the bush has dents formed in an inner surface thereof toform a lubricant film for the sleeve.

Here, the roll of the hot dipping bath comprises a stabilizing roll forsupporting a steel sheet below an air knife when the steel sheet passesaround the roll sunk in the hot dipping bath.

ADVANTAGEOUS EFFECTS

As set forth above, according to preferred embodiments of the invention,the following advantages can be attained from a bearing part of a rollof a hot dipping bath, i.e., a zinc pot roll in a continuous hot dipcoating line, i.e., a continuous galvanizing line.

First, the roll can rotate faster to enhance productivity of the coatedsteel sheet.

Also, according to the invention, the bush and the sleeve in surfacecontact cause wear to occur not locally but uniformly across a contactarea, thereby leading to less wear and smaller depth of wear.

Therefore, despite long use of the bearing device, the bush and sleeveare reduced in wear and kept spaced from each other as initially set.This diminishes vibration of the steel sheet caused by eccentricrotation of the roll and accordingly enhances hot dip coating quality,i.e., galvanizing quality.

In addition, the invention decreases vibration of a frame such as theroll rig, assuring long assembling jobs to be carried out under goodconditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a perspective view illustrating a conventional zinc pot in acontinuous galvanizing line and internal equipment thereof;

FIG. 2 is a front elevation view illustrating a conventional zinc potroll;

FIG. 3 is a schematic view illustrating shaft deviation of aconventional zinc pot roll;

FIG. 4 is a configuration view illustrating a conventional stabilizingroll and a bearing part;

FIG. 5 is a configuration view illustrating a stabilizing roll and abearing part according to the invention;

FIG. 6 is a partial exploded perspective view of FIG. 5;

FIG. 7 is an operational view illustrating shaft deviation of a roll ofa zinc pot according to the invention; and

FIG. 8 is a configuration view illustrating deformation of a bush in abearing device for a roll of a zinc pot according to the invention.

MODE FOR THE INVENTION

Preferred embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

First, FIGS. 5 to 7 illustrate a bearing device 1 for rotatablysupporting a shaft of a roll of a hot dipping bath, i.e., zinc pot in acontinuous hot dip coating line, i.e., a continuous galvanizing line,especially stabilizing rolls.

The bearing device 1 of the zinc pot roll of the invention, as shown inFIGs. includes a sleeve 10, a bush housing 30, bush housing fixed rings40. The sleeve 10 is fastened to a shaft 112 of the roll. The bushhousing 30 has a bush 20 internally fixed to support the sleeve 10, anda curved annular surface 32. The bush housing fixed rings 40 are fixedto both inner sides of a fixed ring housing 50 which is associated witha rig of the zinc pot roll. Each of the bush housing fixed rings 40 hasa curved annular inner surface 42 supporting the bush housing 30 at bothsides thereof and in abutment with the curved annular outer surface ofthe bush housing 30.

In the bearing device of the invention, the bush 20 for supporting thesleeve 10 with which the roll shaft 112 is slidably engaged is insertedinto an inner circumference of the bush housing 30. Here, the bushhousing 30 has a convex spherical outer surface 32 as shown in FIG. 6.

The bush housing fixed rings 40 in abutment therewith have a concavespherical inner surface 42 to be in surface contact with the convexspherical outer surface 32 of the bush housing 30 although the center ofthe roll shaft shifts toward the spherical surface unlike the prior art.

That is, as shown in FIG. 7, in the bearing device of the roll of thezinc pot of the invention, during passing of the steel sheet, the convexspherical outer surface 32 of the bush housing 30 makes surface contactwith the concave spherical inner surface of the bush housing fixed rings40. Otherwise, the steel sheet may be bent due to tension thereof in thezinc pot roll filled with hot molten zinc as shown in FIG. 3.

Therefore, although a central line of the roll shaft shifts from C1 toC2 as shown in FIG. 3, friction does not take place locally andintensively between the sleeve and the bush, but uniformly across acontact area thereof. This restrains uneven wear, which is mostproblematic in the conventional bearing part.

Here, as shown in FIGS. 6 and 7, most preferably, the bush housing 30has a convex spherical outer surface 32 and the bush housing fixed ring40 has a concave spherical inner surface. Accordingly the inner surfaceof the bush housing fixed rings 40 achieves surface contact with theouter surface of the bush housing 30 against friction resistance.

In the end, according to the invention, as opposed to the point contactmade in the conventional molten roll, the outer surface 32 of the bushhousing 30 forms a complete surface contact with the inner surface 40 ofthe bush housing fixed rings 40. This causes abrasion to occur notlocally but entirely across the surface, thereby reducing wobbling ofthe rolls resulting from local abrasion.

Also, as shown in FIGS. 5 and 6, preferably, a buffer film (notillustrated) is interposed between the bush housing ring 34 and a sideof the bush in the vicinity of the bush housing ring 34.

Such a buffer film serves to protect the bush 20 which is highlywear-resistant but modestly vulnerable to impact, from thermaldeformation or impact load.

Furthermore, as shown in FIGS. 5 and 6, the fixed ring housing 50 andthe bush housing fixed rings 40 fixed to both inner sides of the fixedring housing 50 are fastened to inner and outer fixed rings 60, 60′ anda shell housing 70. The inner and outer fixed rings 60, 60′ are disposedat both sides of the fixed ring housing 50 and the shell housing 70 isfixedly engaged with a rig of the roll of the zinc pot (reference sign250 of FIG. 2).

Also, referring to FIG. 5, about four concave surfaces 50 a are machinedon an outer surface of the fixed ring housing 50 at a uniform distance.These surfaces 50 a serve as an area for ensuring easy assembling withthe shell housing 70.

Meanwhile, as shown in FIG. 6, preferably, gaskets G are interposedbetween the inner fixed ring 60 and the shell housing 70, between theouter fixed ring 60′ and the shell housing 70 and between the bushhousing fixed ring 40 and the fixed ring housing 50. The gaskets G blockmolten metal from penetrating inside.

For example, the gaskets G impede the molten metal from penetratingbetween the fixed rings and housings, thereby ensuring easy dissemblingand re-assembling of the bearing device at a room temperature to berecycled.

Moreover, as shown in FIGS. 5 and 6, a fixed pin 80 is inserted throughthe fixed ring housing 50 and into the bush housing 30 to prevent thebush housing from spinning.

That is, as shown in FIG. 6, the fixed pin 80 is threadably mounted in apin hole 30 a formed in a central portion of the outer surface of thebush housing.

The fixed pin 80 accordingly prevents wear that may arise from a slidebetween the bush housing 30 and the bush housing fixed ring 40.

For example, the conventional bearing device disclosed in the U.S patentdescribed above does not have such a fixed pin structure, therebypotentially leading to a slide between housing for fixing a bush and aretainer for fixing the housing.

That is, referring to FIG. 5, with the roll shaft 112 rotating, the bushand the bush housing formed integrally rotate along the roll shaft byfriction of the bush 20 and the sleeve 10. This causes sliding wearbetween the spherical surface of the bush housing 30 and that of thebush housing fixed ring 40. The wear may be worsened to further distancethe bushing housing 30 from the bush housing fixed ring 40, therebywobbling the bush 20.

Therefore, preferably, to prevent spinning of the bush housing, the pinhole 30 a (FIG. 7) is formed on the bush housing 30 to have the fixedpin 80 inserted thereinto.

Meanwhile, the fixed pin 80 constrains the bush housing, keeping it fromspinning beyond a predetermined range (e.g., 2° to 3°).

Therefore, the bush housing (or block) constrained within apredetermined range renders a limited portion worn away with respect tothe shaft. Thus, the bush housing can be installed at a different angleafter a spell of work to reuse an inner surface of the bush. This allowsthe bush to be recycled at least four times.

That is, with a central line of the roll shaft shifting from C1 to C2,the sleeve 10 and the bush 20 contact limitedly. Thus the pin hole canbe positioned adjustably in assembling the bush housing. This changes acontact area between the bush and the sleeve, thereby extending usefullife of the bush.

Meanwhile, as shown in FIG. 5, cover members 90 are disposed to coverfrom a lower end of the bush housing 30 to the bush housing fixed rings40.

Here, as shown in FIG. 5, one of the cover members 90 has an inner sidescrewed to the bushing housing 30 by a fixed bolt 96 and an outer sidefixed between the bush housing ring 30 and the inner fixed ring 60.Likewise, the other cover member 90 has an inner side screwed to theopposing bush housing fixed ring 40 by the fixed bolt 96 and an outerside fixed between the bush housing fixed ring 40 and the outer fixedring 60′.

That is, the cover members have an inner side shaped as an inwardlyconcave ring to be attached to both sides of the bearing part. Suchcover members 90 are made of a heat-resistant material, e.g., SUS 316L.

As shown in FIG. 5, the cover members 90 block molten metal such asmolten zinc or metal compounds such as dross from penetrating betweenthe bush housing 30 and the bush housing fixed ring 40.

Therefore, this overcomes the following problem arising when the bearingdevice of the roll is re-assembled at a room temperature for recycling.That is, in a case where molten metal or metal compounds penetratearound a surface contact area between the spherical outer surface 32 ofthe bush housing and the spherical inner surface 42 of the bush housingfixed ring, the molten metal and metal compounds that have penetratedstick to the spherical outer surface 32 and the spherical inner surface42.

The molten metal, once penetrated and stuck, is hardly removed bycleaning or heating at a temperature higher than a melting point.Consequently in case of recycling of the bearing part, at least a wholebush block of the bush, bush housing and the fixed ring should bedissembled and then re-assembled together.

Then, as shown in FIGS. 2 to 8, in the bearing device 1 of the roll ofthe zinc pot of the invention, dents 20 a such as embossing are formedintegrally in an inner surface of the bush 20 which abuts and supportsthe sleeve 10. The dents 20 a also are filled with molten metal, i.e.,molten zinc to provide a lubricant film for the sleeve 10.

That is, the bush of the invention is made of highly heat-resistantceramics. Here, the dents 20 a are arranged uniformly as shown in FIG. 2in an inner surface of the bush 20, i.e., a surface area in contact withthe sleeve 10 where the roll shaft 112 is assembled.

Accordingly, molten zinc is filled in the dents 20 a between the bush 20and the sleeve 10 which is rotatably supported by the bush 20 so as topush the sleeve 10. This increases lubrication and eventually decreasesfriction between the sleeve and the bush that directly affectsrevolution of the roll shaft.

The bearing device 1 of the zinc pot roll of the invention ensures theroll shaft to rotate very smoothly and minimizes factors for local wear,thereby preferably applicable to the zinc pot roll, especially thestabilizing rolls (reference sign 240 of FIGS. 2 and 3) which aresusceptible to tension of the steel sheet and prone to warping in theirshaft.

Therefore, the bearing device 1 of the invention enhances operability ofthe zinc pot roll 100 in the continuous galvanizing line.

Then an explanation will be given about assembling of the roll shaft ofthe roll bearing device 1 of the invention described above. As shown inFIGS. 5 and 6, first, the highly wear-resistant sleeve 10 is insertedinto the roll shaft 112 formed integral with the roll body 110 of theroll 100 to protect the shaft from skidding wear. Then a sleeve ring 12(see FIGS. 5 and 6) is fixedly welded to the roll shaft 112 not to bedisengaged from the shaft.

Subsequently, the bush 20 for supporting the sleeve 10 having the rollshaft inserted thereinto is shrink-fitted to the bush housing 30, whichis fastened by welding. Here, the bush 20 is made of a ceramic materialhaving excellent wear resistance and uniform friction interface.

Also, as described above, the buffer film (not illustrated) isinterposed between the bush housing ring and a side of the bush in thevicinity of the bush housing ring to relieve thermal deformation loadresulting from differences in thermal expansion.

Moreover, the bush housing 30 and the bush housing fixed ring 40 and thefixed ring housing 50 are assembled as a block with the inner and outerfixed rings 60, 60′ and the shell housing 70 by screws S. Here, asdescribed above, the bush housing 30 has a convex spherical outersurface 32, and the bush housing fixed ring 40 has a concave sphericalinner surface to be in surface contact with the convex spherical outersurface of the bush housing 30.

To facilitate dissembling, assembling and attaching/detaching of thebearing part, gaskets G are interposed between the internal fixed ring60 and the shell housing 70 and between the outer fixed ring 60′ and theshell housing 70 to prevent molten metal from penetrating inside. Inaddition, components are fastened via screws S to achieve more preciseassembling.

Furthermore, the cover members 90 are disposed to cover from a lower endof the bush housing to the bush housing fixed rings to block moltenmetal from penetrating inside.

As a result, in the bearing device 1 of the zinc pot roll of theinvention, the bush housing forms surface contact with the bush housingfixed ring, thereby compensating for any misalignment of a central shaftline of the zinc pot roll with respect to the central line of the bush.This prevents the roll from experiencing decline in rotation forceresulting from increased friction. Notably, this prevents eccentricrotation of the roll, thereby suppressing vibration of the coated steelsheet caused by wobbling of the roll shaft.

While the present invention has been shown and described in connectionwith the preferred embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

1. A bearing device for a roll of a hot dipping bath, in a continuoushot dip coating line comprising: a sleeve fastened to a shaft of theroll of the hot dipping bath; a bush housing having a bush internallyfixed to support the sleeve, and a curved annular outer surface; andbush housing fixed rings fixed to both inner sides of a fixed ringhousing which is associated with a rig of the hot dipping bath roll,each of the bush housing fixed rings having a curved annular innersurface supporting the bush housing at both sides thereof and inabutment with the curved annular outer surface of the bush housing. 2.The bearing device according to claim 1, wherein the curved annularouter surface of the bush housing is convex spherical surface and thecurved annular inner surface of the bush housing fixed ring is concavespherical surface to be in surface contact with the convex sphericalsurface of the bush housing.
 3. The bearing device according to claim 1or 2, further comprising a bush housing ring engaged with an end of thebush housing to fix the bush.
 4. The bearing device according to claim3, further comprising a buffer film interposed between the bush housingring and a side of the bush in the vicinity of the bush housing ring. 5.The bearing device according to claim 1, further comprising inner andouter fixed rings and a shell housing disposed at both sides of andfixed to the fixed ring housing and the bush housing fixed rings, theshell housing fixedly engaging with the rig of the roll of the hotdipping bath.
 6. The bearing device according to claim 5, furthercomprising gaskets interposed between the inner fixed ring and the shellhousing and between the outer fixed ring and the shell housing to blockmolten metal from penetrating inside.
 7. The bearing device according toclaim 1, further comprising a fixed pin inserted through the fixed ringhousing and into a pin hole of the bush housing to prevent wearresulting from rotation of the bush housing.
 8. The bearing deviceaccording to claim 1, further comprising first and second cover memberscovering from a lower end of the bush housing to the bush housing fixedrings to block molten metal from penetrating inside.
 9. The bearingdevice according to claim 8, wherein the first cover member has an innerside fixed to the bushing housing and an outer side fixed between thebush housing ring and the inner fixed ring and the second cover memberhas an inner side fixed to the opposing bush housing fixed ring and anouter side fixed between the bush housing fixed ring and the outer fixedring.
 10. The bearing device according to claim 1, wherein the bush hasdents formed in an inner surface thereof to form a lubricant film forthe sleeve.
 11. The bearing device according to claim 1, wherein theroll of the hot dipping bath comprises a stabilizing roll for supportinga steel sheet below an air knife when the steel sheet passes around theroll sunk in the hot dipping bath.